The present invention relates to a spring retainer for supporting a coil spring such as a valve spring and a spring system having a coil spring combined with the spring retainer.
In recent years, valve train systems are light-weighted to increase the output of car engines and decrease the fuel consumption thereof. For this, some retainers are made of aluminum alloys or titanium alloys so as to reduce inertial weight and decrease spring load.
The aluminum- or titanium-alloy spring retainers are expensive, and compared with iron-based ones, have limits on improving strength, thinness and the like.
They, therefore, have a risk of causing a fatigue fracture if the pressing force of a valve spring causes stress concentration on a spring seat base of the spring retainers.
The spring retainer has a tapered support hole in which a cotter is placed to support the spring retainer with a valve stem. If a strong shock is applied to the valve stem, large force will be applied to the support hole to cause a fracture.
The aluminum- or titanium-alloy spring retainer is structured to support a valve spring made of spring steel, and therefore, has a limit on improving abrasion resistance.
To deal with the problems, there have been proposed a light-metal spring retainer in which abrasion resistive particles are embedded into a surface layer thereof and a light-metal spring retainer whose tapered support hole has a lining made of an iron-based sleeve.
Each of them, however, increases the number of materials or parts, to complicate manufacturing or parts management.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. H07-63020
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2000-161029
Patent Literature 3: Japanese Unexamined Patent Application Publication No. H06-307212